Self-closing stop valves, which are commonly referred to as internal valves, provide protection against discharge of hazardous materials, compressed liquids, and/or gases such as, for example, propane, butane, NH3 (anhydrous ammonia), etc., when transferring the hazardous material between a first location and a second location. Internal valves employ flow control mechanisms that close in response to a sudden excess flow condition due to, for example, a broken, severed, or otherwise compromised flow path. Such flow control mechanisms are commonly referred to as excess flow valves, which are often used in applications requiring an automatic, safe cutoff of fluid flow in response to potential leaks, spills, etc. of potentially dangerous (e.g., combustible, toxic) fluids.
The excess flow valve typically operates based on a pressure differential across the valve. For example, the valve opens when the inlet pressure is approximately equal to the outlet pressure. To equalize the pressure across the valve, internal valves typically employ an equalization member that is actuated to equalize or balance the pressure across the flow control member. An internal valve often requires the use of an actuation mechanism or system such as for example, a lever, a cable control, and/or a powered actuator system. Typically, the actuation mechanism employed allows the equalization member to move between a fully closed position and a fully open position.
In one example, an actuator such as, for example, an external pneumatic actuator may be used to remotely operate the internal valve. Such external pneumatic actuators have a large overall footprint and require an increased amount of space. However, such known internal valves are often used in certain applications having small or tight space constraints, making it difficult to install such an external pneumatic actuator with the valve. Such external pneumatic actuators may also require an additional support member when the valve is installed.
Additionally or alternatively, many known actuation methods are exclusive of one another and, as a result, many manufacturers provide a number of differently designed internal valve product families, each of which is specifically configured to suit the particular needs of a different customer. Such an approach results in manufacturers having to produce and support a large number of diverse products, which is logistically difficult and costly.